The present invention regards the delivery of therapeutic and diagnostic agents to a target site of a patient. More particularly the present invention regards method and apparatus for minimizing the amount of backflow or seepage of therapeutic and diagnostic agents from a target site after the agent has been delivered to the target site.
Accurate and reliable delivery of therapeutic and diagnostic agents is required for the successful execution of numerous medical procedures. In the past, however, the accurate and reliable delivery of these agents during a medical procedure was not always plausible. For example, when a syringe is utilized to deliver an agent to a target site within the body some, if not all, of the injected agent may passively drain from the target site after the needle of the syringe is removed from the target site. This undesirable drainage is accentuated when the target site is an active muscle such as the heart. Here, the agent would not only passively drain from the open channel created by the removal of the needle, it would also be actively forced from the open channel during each muscular contraction.
The drainage of these agents after their injection into the body is problematic for several reasons. First, when a portion of the agent drains away from the injection site it is no longer available to treat the target site and is, consequently, wasted. Moreover, when the agent drains from the target site, but still remains within the body, the agent can interact with and effect other sites within the body of the patient. This unwanted contact and interaction can lead to complications and unpredictable results. In addition, the untimely drainage of the agent from the targeted site may render the agent ineffective because the agent did not remain in contact with the targeted site for the requisite interaction time. Consequently, the agent would need to be reintroduced to the target site through a second procedure. In sum, the uncontrolled drainage of an agent from a targeted site of the body is an objectionable occurrence.
Some conventional processes seek to address this problem. In one known process an erodible polymer is utilized to deliver the drug to a targeted site over a long period of time. In this known process the erodible polymers are blended with a drug and then deposited at the targeted site requiring their use. Over time, the polymer will slowly erode and, concomitantly, delivery the drug to its surrounding area. However, when the targeted site is not readily accessible in the body, substantial operative procedures may be required to properly position the polymer within the body. In addition, when the drug needs to be delivered over a short period of time, the polymer can erode too quickly, allowing the premature drainage of drug. Likewise, if the drug is to be delivered for an extended period of time, the polymer may not erode quickly enough and the drug will be delivered over an unacceptably long time frame.
Accordingly, in view of the potential drawbacks of conventional drug delivery techniques, there exists a need for a method and device that provide for the controlled, localized delivery of agents to target locations in the body which avoid the unwanted shortcomings encountered in the past.
Method and apparatus for diagnostic and therapeutic agent delivery is provided by the present invention. In one embodiment a method for injecting an agent into the body of a patient is provided. This method includes: covering an injection structure having a piercing tip with a coating that contains a first agent; urging the piercing tip of the injection structure into a first targeted site located in the body of the patient; and, maintaining the injection structure in the first targeted site location for a predetermined amount of time. In so doing the agent may be conveniently and accurately delivered to the target site.
In another embodiment of the present invention a drug delivery device is provided. This drug delivery device includes a catheter having a proximate end and a distal end and an injection structure coupled to the distal end of the catheter. In this embodiment the injection structure is covered with a coating that contains an agent. This coating is adapted to release the agent into the body of a patient after the coating enters the body of the patient; again to conveniently and accurately deliver the agent to the target site.